Results from a phase 1b study of blinatumomab-pembrolizumab combination in adults with relapsed/refractory (R/R) diffuse large B-cell lymphoma (DLBCL)

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Background: This open-label, multicenter, phase 1b study evaluated the safety and efficacy of blinatumomab and pembrolizumab combination therapy in patients (pts) with R/R DLBCL (NCT03340766). Methods: Key inclusion criteria included adults with ECOG performance status ≤2 and life expectancy ≥12 weeks. In cycle 1, pts received a continuous intravenous (cIV) infusion of blinatumomab followed by step dosing to the target dose (TD; Table). After a 28-day treatment-free interval, cIV infusion of blinatumomab was administered for 28 days in cycle 2 with the same dose escalations as in cycle 1. Pembrolizumab 200 mg IV was administered once every 21 days starting on day 15 in cohort 1a, and on day 19 in cohorts 2a and 3a. Pts were premedicated with dexamethasone. Dose-limiting toxicities (DLT) were the primary endpoint. The maximum tolerated dose (MTD) was the highest dose level at which ≤1 of 6 or ≤2 of 10 pts experienced a DLT. Results: As of June 10, 2021, 31 pts were enrolled in cohorts 1a, 2a, and 3a (Table). DLTs occurred in 1 (10%) pt in cohort 1a (neutropenia) and 2 (40%) pts in cohort 3a (cognitive impairment, and elevated AST, ALP, and GGT levels). Treatment-emergent (TE) adverse events (AEs) were observed in 31 (100%) pts; grade ≥3 AEs occurred in 29 (94%) pts. The most frequent grade ≥3 TEAE attributed to blinatumomab was nervous system disorders (11 [35%]) and that attributed to pembrolizumab was blood and lymphatic system disorders (5 [16%]). Serious blinatumomab-related and pembrolizumab-related AEs were observed in 15 (48%) and 2 (6%) pts, respectively. Fourteen (45%) deaths occurred; none were treatment-related. Cohort 2a dose was determined as the MTD (Table). In cohort 2a, the objective response rate within 12 weeks of blinatumomab treatment was 30%; the median duration of response in responders (n = 8) was 176.5 (range: 28–680) days. Exposures of blinatumomab and pembrolizumab in this combination study were consistent with historical data for the individual agents. Conclusions: The cohort 2a dosing schedule with TD of 56 μg/day of blinatumomab was established as the MTD. The study was terminated after dose finding because the MTD of blinatumomab in combination with pembrolizumab was lower than the MTD of blinatumomab monotherapy, with no apparent efficacy gain. Clinical trial information: NCT03340766. [Table: see text]

Effect of Blinatumomab vs Chemotherapy on Event-Free Survival Among Children With High-risk First-Relapse B-Cell Acute Lymphoblastic Leukemia: A Randomized Clinical Trial

IMPORTANCE

Blinatumomab is a CD3/CD19-directed bispecific T-cell engager molecule with efficacy in children with relapsed or refractory B-cell acute lymphoblastic leukemia (B-ALL).

OBJECTIVE

To evaluate event-free survival in children with high-risk first-relapse B-ALL after a third consolidation course with blinatumomab vs consolidation chemotherapy before allogeneic hematopoietic stem cell transplant.

DESIGN, SETTING, AND PARTICIPANTS

In this randomized phase 3 clinical trial, patients were enrolled November 2015 to July 2019 (data cutoff, July 17, 2019). Investigators at 47 centers in 13 countries enrolled children older than 28 days and younger than 18 years with high-risk first-relapse B-ALL in morphologic complete remission (M1 marrow, <5% blasts) or with M2 marrow (blasts ≥5% and <25%) at randomization.

INTERVENTION

Patients were randomized to receive 1 cycle of blinatumomab (n = 54; 15 μg/m2/d for 4 weeks, continuous intravenous infusion) or chemotherapy (n = 54) for the third consolidation.

MAIN OUTCOMES AND MEASURES

The primary end point was event-free survival (events: relapse, death, second malignancy, or failure to achieve complete remission). The key secondary efficacy end point was overall survival. Other secondary end points included minimal residual disease remission and incidence of adverse events.

RESULTS

A total of 108 patients were randomized (median age, 5.0 years [interquartile range {IQR}, 4.0-10.5]; 51.9% girls; 97.2% M1 marrow) and all patients were included in the analysis. Enrollment was terminated early for benefit of blinatumomab in accordance with a prespecified stopping rule. After a median of 22.4 months of follow-up (IQR, 8.1-34.2), the incidence of events in the blinatumomab vs consolidation chemotherapy groups was 31% vs 57% (log-rank P < .001; hazard ratio [HR], 0.33 [95% CI, 0.18-0.61]). Deaths occurred in 8 patients (14.8%) in the blinatumomab group and 16 (29.6%) in the consolidation chemotherapy group. The overall survival HR was 0.43 (95% CI, 0.18-1.01). Minimal residual disease remission was observed in more patients in the blinatumomab vs consolidation chemotherapy group (90% [44/49] vs 54% [26/48]; difference, 35.6% [95% CI, 15.6%-52.5%]). No fatal adverse events were reported. In the blinatumomab vs consolidation chemotherapy group, the incidence of serious adverse events was 24.1% vs 43.1%, respectively, and the incidence of adverse events greater than or equal to grade 3 was 57.4% vs 82.4%. Adverse events leading to treatment discontinuation were reported in 2 patients in the blinatumomab group.

CONCLUSIONS AND RELEVANCE

Among children with high-risk first-relapse B-ALL, treatment with 1 cycle of blinatumomab compared with standard intensive multidrug chemotherapy before allogeneic hematopoietic stem cell transplant resulted in an improved event-free survival at a median of 22.4 months of follow-up.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02393859.

Curative outcomes following blinatumomab in adults with minimal residual disease B-cell precursor acute lymphoblastic leukemia

Minimal residual disease (MRD) is the strongest predictor of relapse in B-cell precursor acute lymphoblastic leukemia (BCP-ALL). In BLAST study (NCT01207388), adults with BCP-ALL in remission with MRD after chemotherapy received blinatumomab, a CD19 BiTE^® immuno-oncotherapy, 15 µg/m²/day for up to four 6-week cycles (4 weeks continuous infusion, 2 weeks off). Survival was evaluated for 110 patients, including 74 who received HSCT in continuous complete remission. With a median follow-up of 59·8 months, median survival (months) was 36·5 (95% CI: 22.0-not reached [NR]). Median survival was NR (29.5-NR) for complete MRD responders (n = 84) and 14.4 (3.8-32.3) for MRD non-responders (n = 23; p = 0.002); after blinatumomab and HSCT, median survival was NR (25.7-NR) (n = 61) and 16.5 (1.1-NR) (n = 10; p = 0.065), respectively. This final analysis suggests complete MRD response during blinatumomab treatment is curative. Post-hoc analysis of study data suggests while post blinatumomab HSCT may be beneficial in appropriate patients, long-term survival without HSCT is also possible.

Phase II Trial of the Anti-CD19 Bispecific T Cell–Engager Blinatumomab Shows Hematologic and Molecular Remissions in Patients With Relapsed or Refractory B-Precursor Acute Lymphoblastic Leukemia

Purpose

Patients with relapsed or refractory acute lymphoblastic leukemia (ALL) have a dismal prognosis. CD19 is homogenously expressed in B-precursor ALL and can be targeted by the investigational bispecific T cell–engager antibody blinatumomab. A phase II trial was performed to determine clinical activity in this patient cohort.

Patients and Methods

Thirty-six patients with relapsed or refractory B-precursor ALL were treated with blinatumomab in cycles of 4-week continuous infusion followed by a 2-week treatment-free interval in a single-arm study with a dose-finding stage and an extension stage. The primary end point was complete remission (CR) or CR with partial hematologic recovery (CRh). Major secondary end points included minimal residual disease (MRD) response, rate of allogeneic hematopoietic stem-cell transplantation (HSCT) realization, relapse-free survival (RFS), overall survival (OS), and incidence of adverse events (AEs).

Results

Median age was 32 years (range, 18 to 77 years). Twenty-five patients (69%) achieved a CR or CRh, with 88% of the responders achieving an MRD response. Median OS was 9.8 months (95% CI, 8.5 to 14.9), and median RFS was 7.6 months (95% CI, 4.5 to 9.5). Thirteen responders (52%) underwent HSCT after achieving a CR or CRh. The most frequent AE during treatment was pyrexia (grade 1 or 2, 75%; grade 3, 6%). In six patients with nervous system or psychiatric disorder AEs and in two patients with cytokine release syndrome, treatment had to be interrupted or discontinued. These medical events were resolved clinically.

Conclusion

The data support further investigation of blinatumomab for the treatment of adult patients with relapsed or refractory ALL in a larger confirmatory study.

Effect of anti-CD19 BiTE blinatumomab on complete remission rate and overall survival in adult patients with relapsed/refractory B-precursor ALL

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Background: Blinatumomab is a bispecific T-cell engaging (BiTE) antibody that directs cytotoxic T-cells to CD19 expressing target cells. Methods: In adult patients with relapsed/refractory B-precursor ALL, a phase II dose ranging trial is being conducted to evaluate efficacy and safety of blinatumomab. The primary endpoint is the rate of hematological complete remission (CR) or CR with partial hematological recovery (CRh*) within 2 cycles of blinatumomab treatment. Blinatumomab is administered by continuous intravenous infusion for 28-days followed by a 14-day treatment-free interval. Responding patients can receive 3 additional cycles of treatment or proceed to bone marrow transplantation. Three dose levels were explored as shown in the table. Results: In total 36 patients have been enrolled, 25 are currently evaluable. Seventeen out of 25 treated patients (68%) reached a hematological CR/CRh* and a minimal residual disease (MRD) response (MRD level <10-4) within the first 2 cycles. Five out of 17 responders (29%) showed a CRh* due to partial recovery of platelets. For the first 18 patients, response duration is 7.1 months and the median follow-up time for overall survival (OS) is 9.7 months (median not reached). Six cases of relapses have been recorded of which 3 were CD19+, and 3 CD19-. As final dose 5 µg/m²/day in week 1 and 15 µg/m²/day for the remaining treatment (cohort 2a and 3) was selected. In these cohorts (n=12), the most common treatment emergent adverse events (TEAEs, all grade 1-2) were pyrexia (67%), headache (33%) and tremor (33%). TEAEs of grade ≥3 (7 in 5 patients, no grade 4), irrespective of relationship, were infections, confusion, epilepsy, hypertension and thrombocytopenia. Conclusions: The final dose was well-tolerated and produced an exceptionally high complete remission rate. A global phase 2 study to confirm these data is underway. [Table: see text]